The goal is to determine the structure of the LH/hCG receptor and the nature of its interactions with the hormone and associated molecules including adenylate cyclase. We will pursue the following specific objectives: 1. Micropurification and characterization of receptor subunits (peptide maps, finger-prints, amino acid sequence and ADP-ribosylation). 2. Determination of receptor subunit organization (cytoplasmic and extracellular domains, neighboring subunits, location of subunit crosslinks, phosporylation, fatty acylation and the presence of carbohydrates). 3. Study of hormone-receptor interactions; sites in the hormone crosslinked to the receptor, the preference and the order of the affinity labeling of receptor subunits by each of the hormone (LH, hCG and deglycosylated hCG) subunits. 4. Study of interactions of the receptor with the adenylate cyclase system. 5. Further preparation of monoclaonal antibodies to the receptor.